The invention relates to a circuit arrangement to monitor the time spacing of square-wave signals.
To monitor the time spacing of square-wave signals consisting of first square-wave signals and second square-wave signals appearing between the former it is expedient to generate with each first square-wave a time window which defines an expectancy period for a subsequent corresponding second square-wave signal. It would be imaginable for the generation of the time window to use two monostable flip-flops, the first one marking the beginning and the second one the end of the time window. Such a circuit arrangement is relatively costly and, in particular, because of the relatively great inaccuracies of the internal resistance of monostable flip flops, balancing is required.